Random copolymer polypropylenes are widely used for injection and blow molded packaging applications. These polypropylenes are prepared by copolymerizing propylene with a relatively small amount of ethylene, typically less than 5 wt % based on the total polymer weight. The products have much improved clarity compared to propylene homopolymer and the impact strength is somewhat better than that of the homopolymer. However, the latter property, especially at low temperatures, is not sufficiently high for many applications where the finished articles of manufacture are to be exposed to low temperatures. The impact strength can be improved by addition of rubbery materials such as amorphous ethylene-propylene rubber polymers or ethylene-propylene block copolymers. Also, blends of one or more of the above components with polyethylene have been disclosed in the art as a further means of improving the impact strength especially at low temperatures. Although there has been reported favorable results in attaining the desired improvement in impact strength by these blending techniques, they have always been accompanied by a detrimental reduction in desired clarity which precludes the use of the resin blend in many applications.
It is, therefore, an object of the present invention to provide a high impact propylene polymer composition, having a clarity at least as good or better than that of a random copolymer polypropylene.